This invention relates to syringe pumps.
Syringe pumps are used to supply medication to a patient from a pre-filled syringe via an infusion line. The syringe pump applies a force to the plunger of the syringe to drive medication into the infusion line at a controlled rate. It is common to have some provision to detect occlusion to flow of liquid out of the pump, such as caused by kinked tubing, and to respond to this by stopping the pump and sounding an alarm. The occlusion may be detected by measuring the force exerted on the plunger head by the pump driver, to detect excessive force. As described in GB2352637, the plunger head retainer itself may include a force sensor. The excess force produced until the occlusion is detected is accommodated by deformation of the elastic components, such as the fluid tubing and the syringe plunger head. When the pump is stopped, therefore, the medication fluid upstream of the occlusion is subject to compressive forces. When the occlusion is cleared, such as by straightening kinked tubing, the compressive force may cause a bolus of medication to flow to the patient. This can, in some situations, present a hazard to the patient.
WO97/07843 describes a peristaltic pump where the pump is reversed on detection of a possible occlusion and is then driven forwardly again before generating an alarm.